Thermostatic switch



Jan. 2, 1934. F. s. DENISON ET AL THERMOSTATIC SWITCH Filed June 18, 1931 INVENTORS FREDERICK 5. DENISON NIEL TAYLOR ATTORNEYS Patented Jan. 2, 1934 Q 7 1,941,540 THERMOSTATIC SWITCH Frederick S. Denison and Daniel G. Taylor, Minneapolis, Minn., assignors to Minneapolis Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application June 18, 1931. Serial No. 545,349 22 Claims. (01. 200 138) This invention relates to thermostatically con- 8 at one end of the tubular member, and jourtrolled switches, and is particularly concerned naled at the opposite end at 9 in the rear wall of with a stack thermostat construction, adapted the casing 1. The tubular member is provided to be arranged in the stack or flue of a furnace, with the usual ventilating openings 10 which as and including a plurality of switches and means sist in preventing undue heating of the casing. so for differentially operating the same conform- Attached to the shaft 7 is the usual thermostatic ably to temperature changes. element 12 in the form of a spiral bimetal ribbon An important object is to provide a stack therhaving one end connected as at 14 to the tubular mostat having two switches or contacts which are member 4, and having the other end connected as controllable by a common thermal means. so at 13 to the shaft 7. It will be understood that 5 that on a rise in temperature one contact is on change in temperature, the shaft is rotated closed prior to the opening of the other, and so as the result of expansion or contraction of the that upon temperature fall that contact which element 12. was closed on a rise in temperature opens be- Mounted upon the shaft 7 within the casing 15 fore the closing of the other contact. Another are the switch control elements which primarily object is to provide overlapping contact action consist of two spur gears or toothed disks which during temperature run in one direction, and cooperate with movable switch members in a non-overlapping action during temperature run manner to be presently described. Two disks are in an opposite direction. The device finds valuemployed, one fixed and one rotatablerelative to 20 able application at present for controlling a shaft 7. The ratchet-like action of the disks burner apparatus in which hot and cold conupon the movable switch elements is fully detacts are employed, and in which itis desirable scribed in the patent to Cyr, for Thermostatic to have the hot contacts closed prior to the breakcircuit controlling apparatus, Number 1,768,892, ing of the cold contacts during temperature rise, issued July 1, 1930. The present switch device is 25 and in which it is further desirable to have the adapted to control two switches or contacts in 5 hot contacts broken before the cold contacts a certain manner, instead of a single switch, as close, during a fall in temperature. It will later disclosed in the patent, but the action of the appear, however, that the invention also protoothed disks on the switch arms is here subvides means whereby an overlapping action be stantially the same as in the patent.

0 tween a plurality of contacts can be obtained The shaft 7 is counter-turned as at 15 and the 5 when the temperature moves in one direction, counter-turned portion is terminally threaded and so that there is no overlapping action when as at 16. The counter-turning provides a shoulthe temperature moves in an opposite direction. der 1'7 and engaged with the counter-turned por- Features of the invention include all details tion 15, and abutting shoulder 17 is a bushing 18.

5 of construction, as well as the broader ideas of Arranged upon the reduced portion 15 is a means inherent in the disclosure. sleeve 19 of insulating material which abuts the Objects, advantages and features of the inbushing 18 and upon this insulatirg sleeve is vention will be set forth in the description of the a cup-shaped insulating member 20 which also drawing forming a part of this application, and abuts the bushing 18 and caps it. Also mounted 40 in said drawing on the insulating sleeve 19 is a toothed disk Figure 1 is avertical longitudinal section; and 22 and upon the insulating sleeve 19 is also Figure 2 is an end elevation, showing the parts mounted a sleeve 23 which abuts the disk 22. positioned as before application of heat to the This sleeve 23 has a reduced portion 24 formthermostatic element. ing a shoulder 25 and upon the reduced por- 4 Numeral 1 indicates a suitable casing for hous- I tion is rotatably mounted a tocthed disk 27 which ing switches and part of the means for operatabuts the shoulder 25. This spur-gear-like disk ing them. Numeral 2 indicates a cover for the 27 is slotted as at 28. see Figure 2, the slot casing. The bottom of the casing has the usual being curved and having the center of curvature tubular cable outlet member 3. Suitably atin the axis of the shaft 7. On the outer face 50 tached to the back of the casing perpendicularly of this disk is arranged a slotted plate 29, the m thereto is a tubular member 4, which member slot 30 of which registers with the slot 28 of is adapted to pass through the wall of a stack the disk. This plate swings on the reduced porand is suitably secured thereto by means such tion 24, and a set screw ill secures the plate in as a circumscribing bracket 6. Within the tubuany adjusted position. The plate is segmental 55 lar member is a shaft 7 suitably journaled as at and covers only a portion of the face of the disk, and provides at one side a radial portion 32, as a stop. Disk 22 carries a pin 34 which passes loosely through the slot 28 of the disk 27, and normally, as when the thermal element 12 is cold, engages the shoulder 32 as shown in Figure 2. That portion of the slot between the shoulder and the end of the slot provides a lost motion connection between the fixed disk 22 and the movable disk 27. The degree of lost motion can be varied at will. On c unter-clockwise motion of the shaft '7, this fixed disk 22 moves a certain distance before the pin 34 engages the end 35 of the slot of the movable disk. The purpose is to cause one of the contacts to open only after a predetermined degree of rotation of shaft 7 has occurred, and after the other contact has closed.

Mounted on the insulating sleeve 19 and abutting the end of the sleeve 23 is a washer 36 which prevents undue axial motion of disk 27. Also carried by the sleeve 19 is a cup 3'! (similar to the cup 20), the inner surface of which lies in a plane beyond the end of the sleeve 19. Within the cup and engaging its inner surface is a washer 38, and engaged with this washer is a split washer 39, and a nut 40 clampingly engages the split washer to secure the elements and to clamp the disk 22, by transmission of clamping pressure through the washers 39, 38, cup 3'7, washer 36, sleeve 23, cup 20, and bushing 18. It is obvious that other suitable means may be used for fixing the disk 22 for rotation with the shaft '7, and for mounting the disk 2'? for rotation relative to said shaft, and for suitably insulating the disks from the shaft.

Suitably attached within the casing l is a block 42 of insulating material, and to this block are attached (see Figure 2) two plates respectively indicated 43-44. Upon the plate 43 is mounted a flexible contact arm 45, and upon the plate 44 is mounted a flexible contact arm 46. Suitably secured to a common support 48, in turn mounted on an insulating block 42 is a flexible contact arm 49 having a contact stud 50 engageable with corresponding stud of the arm to close the circuit. The arm 49 is biased to move automatically to closed circuit position. For convenience, the arms 45 and 49 are referred to as the hot contacts. Associated with the arm 49 is a flexible arm 52, the terminal of which is engaged with the teeth of the disk 22. Figure 2 shows the parts positioned as whenithe thermal element 12 is cold, and, therefore, contacts 45-49 areopen. The element' 52 engages the arm 49 and springs it to the position shown, from which position it will automatically follow the element 52, when disk 22 moves in counter-clockwise direction. The stud of arm 49 passes loosely through an opening 53 of blade 52 as shown in Figure 1. On counter-clockwise rotation of disk 22, arm 49 follows the blade 52 until the contacts are closed, after which blade 52 can move away from blade 49 on continued rotation of the disk 22 in the same direction, in this instance as the temperature continues to rise. During the continued motion in counter-clockwise direction, the control element 52 is successively releas-,d and moves against the following toothas a stop, but without sufficient movement to permit the control member to move the switch arm 49 from its closed-circuit position.

Attached to the support 48 is an extension having a portion 61 to which is attached a spring metal arm 62 bent intermediately to provide a cam projection 63, in this instance convex,

contact arm 64 which has a contact stud 65 engageable with the corresponding stud of contact arm 46. Arm 64 is also biased to move to circuitclosed position, and its outer end is engaged by the teeth of disk 27, and the arm has an opening 66 through which the extension 62 passes. When the arm 64 is in switch-closed position, its terminal is disposed at one side of the cam 63 and when in switch-open position, at the opposite side of the cam.

The cam projects beyond the outer side 67 of the opening 66, so that the spring arm 62 is flexed from its initial position each time the switch arm is urged a suflicient distance in either direction against the cam. The cam acts as a stop to secure the switch in either of its control positions. When positioned as in Figure 2 the cam acts to hold the switch arm 64 in switch closed position. When positioned at the opposite side of the cam, the cam acts to hold the arm in switch open position. As the arm rides over the peak of the cam and after it has reached a. position slightly to one side of the peak, the action of the spring arm 62 is capable of forcing one of the inclined planes against the arm to accelerate its motion in a corresponding direction. This feature may be applied for causing quick opening and closing of any switch.

The screws 69 of plate 44 are connected by a conductor 70 with binding post '71, the conductor '70 being embedded in the insulation 42. The screws of plate 43 are connected by embedded conductor '12 with binding post '73. The screws '78 are connected by bar '76 with binding screw 77.

Operation Referring to Figure 2: assume the rotation of the shaft in counter-clockwise direction, due to a rise in temperature. During the first part of this rotation, the lost motion connection between the disk 22 and the disk 27 permits a movement of disk 22 without movement of the disk 27, which disk 2'7 is held against movement by the switch arm 64. The control member 52 now moves to the right and switch arm 49 follows it until that arm reaches switch-closed position. After this closure, the pin 34 (which has been travelling in the slot 28) engages shoulder 35 and on continued motion of the shaft in counterclockwise direction, disk 27 is moved in the same direction, and arm 64 is moved to the right, and engages the cam and depresses the spring arm 62 and passes to switch open position, where it is held by the base portion of the cam, acting as a stop.

When the temperature falls, the direction of the shaft rotation is reversed, and it has a clockwise motion. During the forepart of this motion, disk 2'! is held against rotation as a result of the engagement of its teeth with the arm 64, which is releasably held in switch-open position by the cam 63. The first action is by the disk 22 which moves the control member 52 against switch arm 49 and opens the switch. During this movement, the pin 34 is moving in the slot 28 in a direction away from stop 35 formed by the end of the slot, and after a timed interval, determined by stop spacing, the pin engages stop 32 and disk 27 also begins to rotate in clockwise direction, resulting in movement of the switch arm 64 against the cam, again depressing the arm 63. passing beyond the peak of the cam to switch closed position where it is held by the base portion of the cam, acting as a stop.

We claim'as our invention:

1. A pair of switches, a movable member and separate means thereon adapted to control re-- spective switches, and a lost motion connection between said means adapted to cause one means to move in advance of the other and then move that other, whatever the direction of motion of said movable member.

2. A pair of switches biased to move tocircuit closed position, a movable member, separate means thereon adapted to control respective switches, and a lost motion connection between said means adapted to cause one means to move in advance of the other, and then move that other.

3. A pair of switches each biased to move to closed circuit position and in opposite directions to such position, a movable member and separate means thereon adapted to control respective switches, and a lost motion connection between said means adapted to cause one means to move in advance of the other and then move that other, whatever the direction of motion of said movable support.

4. A pair of switches biased to move to circuit closed position, a movable member and means for moving it in response to temperature changes, separate means operated by the member and adapted to control respective switches, and before temperature rise to secure one switch in closed position and the other in open position, and a lost motion connection between said means adapted to cause one means to move in advance of the other and then move that other.

5. A pair of switches biased to move in opposite directions to circuit closed position, a movable member and means for moving it in response to temperature changes, separate means operated by the member and adapted to control respective switches, and before temperature rise to secure one switch in closed position and the other in open position, and a lost motion connection between said means adapted to cause one meansfto move in advance of the other and then'move that other.

6. First and second switches, a movable member and means for moving it in response to temperature changes, first and second means adapted to control corresponding switches and before temperature rise to secure one switch in circuit open and the other in circuit closed position, a lost motion connection between said means adapting one means to close the first switch before the 5 other means opens the second when the member moves in one direction, and adapting the first means to open the first switch before the second means acts to close the second switch when the member moves in an opposite direction, including means for latching the second switch in open position during the opening motion of the first switch.

'7. First and second switches biased to move in opposite directions to circuit closed position, a movable member and means for moving it in response to temperature changes, separate means adapted to control respective switches, and before temperature rise to secure one switch in circuit open, and the other in circuit closed position. a lost motion connection between said means by which to cause closure of the first switch before opening the second when the support moves in one direction and by which to cause opening of the first switch before closing the second when the support moves in an opposite direction.

8. A shaft, a pair of tooth disks thereon one fixed to the shaft and the other rotatable upon the shaft, switch arms one for each disk adapted to be controlled by the teeth of the disks, the arms being biased to move in opposite directions to switch-closed position, means adapted to releasably latch that arm controlled by said rotatable disk in open circuit position, and means establishing a lost motion'connection between thedisks, whereby that arm controlled by the fixed disk reaches switch closed position before the other disk moves its arm to switch open position.

9. A pair of switches each having a movable arm biased to move automatically to circuit closed position, the closing motion of the arms being in opposite direction, a shaft, first means fixed for movement with the shaft and adapted to move one of the arms, second means rotatable relative to the shaft and adapted to control movement of the other arm, and lost motion connection between said arm control means including spaced stops whereby the second arm moving means can be entrained by the first on rotation of the shaft in either direction.

10. A thermostatic switching mechanismincluding a movable member, a thermal element adapted to move said movable member in opposite directions in correspondence to rise and fall of temperature, a pair of switches, each biased to ,auto-; matically close and separate means on said movable member for independently controlling respective switches, and a lost motion connection between said separate means including spaced 110 stops adapting one of said means to have a predetermined motion independently of the other, and to then move that other, one of said switches being normally opened and the other closed before heat is applied to said thermal element.

11. A pair of switches,a movable member have ing toothed disks thereon adapted to control ree spective switches one of the disks being fixed and: the other movable relative to the movable member, and means connecting the disks and adjustable either to cause the disks to move in unison or to cause one disk to move in advance of the other and then move that other.

12. A pair of switches, a movable member and separate means thereon adapted to control respec- 135 tive switches and means connecting the last men tioned means andadiustable either to cause the means to move in unison or to cause one means to move in advance of the other and then move that other.

13. A pair of switches, a movable member having thereon toothed disks, one fixed and one movable, each switch having a control member engageable by teeth of respective disks, and means connecting the disks and adjustable to cause one to move in advance of the other and then move that other whatever the direction of motion of said movable member, and thermostatic means for moving said movable member.

14. A control element, a shaft and means for automatically reversing its rotation conformably to variations in physical conditions, means on the shaft for controlling the control element, and an adjustable lost motion connection between the shaft and the last mentioned means for allowing the shaft to rotate a predetermined number of angular degrees before the control element is moved.

15. A device of the class described comprising a shaft and means for automatically reversing 1 its rotation conformably to variations in physical conditions, a pair of disks upon said shaft one movable with the shaft and one rotative thereon, the rotative disk having a slot and the fixed disk having a pin movable in the slot, stop means adjustable to vary the length of the slot, and switches one independently controlled by each disk.

16. A shaft and means for automatically reversely rotating it conformably to changes in physical conditions, a switch control element, and means on the shaft for moving the control element from one switch control position to another including a lost motion connection for permitting a predetermined degree of motion of the shaft in either direction without motion of the switch control element, a resilient element adapted to be flexed by the control element as it moves from one control position to another, and having a shoulder which secures the control element in one control position while the control element moving means is idle as the result of the lost mention connection.

17. A pair of switches of the open contact type, a shaft and means for automatically reversing its rotation conformably to variation in physical condition, and means on said shaft for differentially controlling the switches conformably to direction of moLion of the shaft including the overlapping control in one direction.

18. A switching mechanism of the class described comprising, in combination, an actuator movable in reverse directions, first and second switches, means associated with the actuator and one of said switches for moving the latter to closed circuit position upon movement of the actuator in a first direction and for moving the same to open circuit position upon reverse movement of the actuator, and means associated with the actuator and the other of said switches for moving the same to open circuit position with a relatively fast motion afler said first mentioned switch has been moved to closed circuit position upon movement of the actuator in the first direction, and for moving the same to closed circuit posiiion with a relatively fast motion after said first named switch has been moved to open circuit position upon reverse movement of said actuator.

19. A switching mechanism of the class described comprising, in combination, an actuator movable in reverse directions in response to changes in temperature, first and second switches, means associated with the actuator and first switch for moving the latter to closed circuit position upon movement of the actuator in a first direction as a result of rise in temperature and for moving the same to open circuit position upon reverse movement of the actuator as a result of fall in temperature, and means associated with the actuator and second switch for moving the same to open circuit position with a relatively fast motion after said first switch has been moved to closed circuit position upon movement of the actuator in the first direction, and for moving the second switch to closed circuit position with a relatively fast motion after said first switch has been moved to open circuit position upon reverse movement of said actuator.

20. A switching mechanism of the class described comprising, in combination, an actuator movable in reverse directions, first and second switches, means associated with the actuator and first switch for moving the latter to closed circuit position upon movement of the actuator in a first direction and for moving the same to open circuit position upon reverse movement of the actuator, and means including a lost motion connection associated with the actuator and second switch for moving the same to open circuit position with a relatively fast motion after said first switch has been moved to closed circuit position upon movement of the actuator in the first direction and for moving the second switch to closed circuit position with a relatively fast motion after said first switch has been moved to open circuit position upon reverse movement of said actuator.

21. A switching mechanism of the class described comprising, in combination, an actuator movable in reverse directions, a first switch, connecting means between the actuator and first switch for moving the latter to closed and open circuit positions upon reverse movements of the actuator, a second switch, and separate connecting means between the actuator and second switch for moving the latter to open and closed circuit positions upon reverse movements of said actuator, said lost motion connecting means permitting movement of said first switch to closed and open circuit positions prior to movement of said second switch to open and closed circuit positions, whereby the circuits controlled by said switches are concurrently energized for a time upon movement of the actuator in one direclion only.

22. A switching mechanism of the class described comprising, in combination, an actuator movable in reverse directions in response to temperature changes, a first switch, conn'ecting means between the actuator and first switch for moving the latter to closed circuit position on temperature rise and open circuit position upon temperature fall, a second switch, and separate connecting means between the acluator and second switch for moving the latter to open circuit position on temperature rise and closed circuit position upon temperature fall, said lost motion conneclion permitting movement of said first switch to closed and open circuit positions prior to movement of said second switch to open and closed circuit positions whereby the circuits controlled by said switches are concurrently energized for a time 

